The fiery ''explosion'' that destroyed part of a Dunedin bar is most likely to have started accidentally, a fire investigator says.
East Otago Southland fire risk management officer Cathy Trevathan said the investigation into the fire in the office of the Bog Irish Bar on August 2 was continuing but some conclusions were likely.
The fire had started in the small office on the top floor of the pub, on the corner of London and George Sts, after some ''smoking material'' had been discarded.
Ms Trevathan would not reveal what she believed the discarded material was until the investigation was over but it should have been disposed of in a metal or concrete container.
After the fire started, the airflow to the office caused a ''flashover'' - the near-simultaneous ignition of most of the directly exposed combustible material in an enclosed area.
''It caused an almighty explosion.''
The alarm system in the building gave firefighters enough warning to contain the fire to the office.
The bar and building owner, Max Bremner, of Christchurch, said he was ''relieved'' the fire was not arson, though he never believed it was.
If someone had wanted to burn his pub down, then starting a fire on the top floor made no sense, he said.
The building was insured and the office would be restored. Bar manager Greg Wilson said the office was ''the size of a caravan'' and everything was destroyed.
The melted electronics in the office yesterday included computer screens and a cash register.
The smell of smoke in the restaurant and bar dissipated after two days, Mr Wilson said.
The pub closed after the fire and reopened five days later.
Mr Wilson thanked the firefighters for their quick response.
''It could have been a hell of a lot worse.''
